Flat bed tractor trailers having a retractable tarping system are used to transport a wide variety of freight, much of which freight cannot be loaded into conventional van type transport trailers having in-situ walls and roof. The tarping system comprises a tarpaulin supported by a plurality of vertically disposed frame members that span across the bed of the trailer and are attached at each of their opposite free ends to a respective trolley having rollers that engage an elongate track disposed along each side of the trailer. The trollies are manually urged along the elongate tracks to move the tarpaulin system between its trailer enclosing configuration and its open configuration. A typical prior art track, as taught in Canadian Patent 1,331,635, comprises an inverted "U"-shaped channel with an additional lower horizontal flange to support the wheels of the trolleys. Another typical prior art track comprises a "C"-shaped channel with an outer upwardly projecting flange, as produced by TILL-FAB LTD. of Norwich, Canada, and as disclosed in a published promotional brochure entitled "ROLL-TITE.sub.TM " Flat Deck Tarping Systems. Yet another prior art track is produced by the present inventor, and has a "C"-shaped channel disposed above and inverted "U"-shaped channel.
For flat bed trailers having any type of prior art tarping system tracks installed thereon, a transported load must be secured by straps anchored at their ends to the sides of the trailers and tightly spanning across the trailer, over or through the load on the trailer. Typically, in order to accommodate the anchoring of the ends of such straps, the elongate tarping system tracks are mounted in spaced relation from the sides edges of the trailer bed by means of a plurality of metal webs, or similar spacing means interposed between the track and the side edges of the trailer. In this manner, the straps are able to pass between the track and the edge of the trailer bed so as to hook onto an appropriate anchoring means, such as the metal webs. Such spacing of the elongate tracks from the side edges of the trailer bed presents a serious problem, as it significantly, and in many cases unacceptably, adds to the overall width of the trailer bed. The overall width of a trailer bed is limited in many jurisdictions to 102 inches, including the elongate tracks and trolleys of the tarping system. Since most tarping systems are installed onto existing trailers, there is typically very little room, if any, for the inclusion of the elongate tracks and trolleys, and in some instances, trailers having tarpaulin systems installed thereon are wider than the maximum width permitted by local laws. Accordingly, providing spacing between the trailer bed and the elongate track, in order to receive the ends of the straps, is an extremely inefficient use of space, and may constitute an unacceptable use of space, as it may be an illegal practice.
In order to preclude over-width flat bed trailers, the elongate tracks of the tarping system may be secured directly to the side edges of the trailer, with no spacing between the elongate tracks and the side edges of the trailer, In this case, the straps pass through small cut-out sections in the floor of the trailer bed inboard of the side edges of the trailer bed. However, these openings reduce the effective carrying width of the trailer, which is highly undesirable. Moreover the provision of such openings in the trailer may interfere with the structural integrity of the trailer and will, in any event, constitute a significant additional capital cost for the trailer.
Another problem associated with prior art elongate tracks is that of receiving and retaining dirt and small debris in their interiors, which dirt and debris preclude the smooth operation of trolleys along the length of the tracks.
It is an object of the present invention to provide a track and trolley assembly for use with a tarpaulin enclosing system on a flat bed trailer, which track and trolley assembly precludes the inclusion of a space between the track and the side edge of the flat bed trailer.
It is another object of the present invention to provide a track and trolley assembly for use with a tarpaulin enclosing system on a flat bed trailer, which track and trolley assembly is mountable onto existing flat bed trailers without increasing the overall width of the trailer beyond a legal limit.
It is yet another object of the present invention to provide a track and trolley assembly for use with a tarpaulin enclosing system on a flat bed trailer, which track and trolley assembly precludes the need for cut-out sections in the floors of flat bed trailers for receiving tie-down straps therethrough.
It is yet another object of the present invention to provide a track and trolley assembly for use with a tarpaulin enclosing system on a flat bed trailer, which track and trolley assembly substantially precludes the entry of dirt and small debris into its interior.